Wavefront aberrations of human eyes have been focused on by visual researches for a long time. In 1997, Liang and Williams firstly incorporated a Hartmann sensor into an adaptive optics system to achieve static compensation for the aberrations of the human eyes and thus to achieve supernormal vision (Liang, J., D. R. Williams, and D. T. Miller, Supernormal vision and high-resolution retinal imaging through adaptive optics. J. Opt. Soc. Am. A, 1997. 14(11): p. 2884-2892). As the adaptive optics technology proves to be successful in the visual optics field, there are more and more researches in the role of high-order aberrations of the human eyes in visual functions.
An Adaptive Optics Visual Simulators (AOVS) is an important tool in the visual optics researches. The AOVS simulates effects of the aberrations of the human eyes in the visual functions by measuring variations of the visual functions of the human eyes under different states of aberrations. In 2001, research groups from Rochester University, United States and from Murcia University, Spain independently proposed schemes for closed-loop dynamic correction of the aberrations. Thereafter, many researchers employ AOVS's to explore relationships between the aberrations of the human eyes and the visual functions (Fernández, E. J. and P. Artal, Study on the effects of monochromatic aberrations in the accommodation response by using adaptive optics. J. Opt. Soc. Am. A, 2005. 22(9): p. 1732-1738; Lixia, X., et al., Higher-Order Aberrations Correction and Vision Analysis System for Human Eye. ACTA OPTICA SINICA, 2007. 27(5): p. 893-897). Those visual simulators are all monocular systems. However, binocular vision is a normal case for the human eyes. Therefore, it is natural and necessary for the researches to transit from monocular vision to binocular vision. For example, in 2009, E. J. Fernández, et al. from Murcia University, Spain proposed a binocular adaptive optics visual simulator for researches on contrast sensitivities when there are different combinations of spherical aberrations superimposed on a pair of eyes (Fernández, E. J., P. M. Prieto, and P. Artal, Binocular adaptive optics visual simulator. OPTICS LETTERS, 2009. 34(17): p. 2628-2630). Later, Ramkumar Sabesan, et al. from Rochester University, United States proposed in 2010 a binocular adaptive optics visual simulator for researches on effects of binocular aberrations on visual acuities and contrast sensitivities.
Recent researches show that accommodative lag of the eyes is directly relevant to myopia (L. Chen, P. B. Kruger, H. Hofer, B. Singer, and D. R. Williams, Accommodation with higher-order monochromatic aberrations corrected with adaptive optics, J. Opt. Soc. Am. 2006.V23(1), 1-8). Further, some of the high-order aberrations of the human eyes are closely associated with causes of the accommodative lag (E. Gambra, L. Sawides, C. Dorronsoro, and S. Marcos, Accommodative lag and fluctuations when optical aberrations are manipulated, Journal of Vision 2009.9(6), 1-15). Therefore, researches on effects of the aberrations of the human eyes on accommodation responses are valuable for exploring of causes and also clinic prevention and treatment of myopia. However, in a natural visual field, accommodation, vergence and pupil constriction are associated with each other, and precise cooperation among them is necessary for a single clear binocular vision. Here, “vergence” refers to that the two eyes focus on an external object by adjusting an angle included between their respective lines of sight, to achieve a single binocular vision. The above binocular visual simulators proposed by Murcia University and Rochester University are both based on a far viewing state where visual axes of the two eyes are parallel to each other, and thus are unsuitable for researches on the accommodation responses.